Ablative injectors

ABSTRACT

An injector according to the present disclosure comprises an ablative body having an injector face adapted to form a portion of a rocket combustion chamber. A plurality of ports is disposed in the injector face for injecting propellant into the combustion chamber and manifold means is integrally formed within the body for supplying propellant to said ports. According to one feature of the present invention, a mold is provided for casting the ablative injector. The injector formed by means of the mold according to the present disclosure is a unitary ablative injector for injecting propellant into the combustion chamber of a rocket engine.

United States Patent 2 39.74, 200 A; 239/265.l5, DIG. 19, 127.1, 127.3,

References Cited UNITED STATES PATENTS 3,174,283 3/1965 Crocco 60/39723,242,668 3/1966 Ellis 60/3974 3,285,013 [1/1966 Bell 60/258 3,362,l661/1968 Sippel 60/258 Primary Examiner-Douglas Hart Attorneys- Edward O.Ansell, D. Gordon Angus and Taylor M. Belt ABSTRACT: An injectoraccording to the present disclosure comprises an ablative body having aninjector face adapted to form a portion of a rocket combustion chamber.A plurality of ports is disposed in the injector face for injectingpropellant into the combustion chamber and manifold means is integrallyformed within the body for supplying propellant to said ports. Accordingto one feature of the present invention, a mold is provided for castingthe ablative injector. The injector formed by means of the moldaccording to the present disclosure is a unitary ablative injector forinjecting propellant into the combustion chamber of a rocket engine.

PATENTED AUG] 7 IBYI 3, 599 ,430

INVENTOR. 05527 M keo/wea oa rmu a ATTOR NEY ABLATIVE INJECTORS Thisapplication is a continuation-in-part of my earlier application Ser. No.771,388 filed Oct. 29, 1968, entitled Ablative Injectors, now abandoned.

This invention relates to ablative injectors and to molds forconstructing ablative injectors.

Heretofore, injectors for rocket engines and the like have beenconstructed of metal or other thermally destructive material and havebeen subjected to failure due to thermal destruction of the injectorface. Thermal destruction is most likely to occur when one or more ofthe following conditions exists: (1) When the combustion pressure in therocket chamber is relatively low so that the pressure differentialacross the injector face is also relatively low, and thereby limitingthe discharge of propellant into the combustion chamber; (2) when thelocal heat-transfer rates are relatively high at the injector face; and(3) when the injector face is insufficiently cooled.

Heretofore, injectors have been cooled by means of a cooling system soas to dissipate heat from the injector face. Particularly, coolingsystems have been utilized whereby coolant flows to the injector face.However, such cooling systems have not been completely effective due tothe fact that failure of the cooling system or improper regulation ofthe coolant flow can cause a reduction of coolant flow to the injectorface thereby resulting in localized destructive thermal conditions, orhotspots," on the injector face. Also, the difficulty in regulating thecoolant flow to the injector face has often made such cooling systemscostly as well as bulky.

It has been difficult to maintain the integrity of the ports andmanifolds in molded ablative devices. Thermosetting or ablative resinshave a propensity for interchannel leakage due to porosity,delamination, cracking or other similar flaws. For rocket enginecomponents, it is necessary to assure reliability through qualitycontrols,

The present invention eliminates the major'problems associated withcooling systems for injectors by providing an uncooled injectorconstructed of an ablative material.

It is an object of the present invention to provide an injectorconstructed of an ablative material which requires no cooling system.

Another object of the present invention is to provide an uncooledinjector which is constructed of a unitary ablative body.

A further object of the present invention is to provide an uncooledinjector having ports and channels or manifolds with a thin lining of asilicone or fluorocarbon plastic material.

An injector according to the present invention comprises an ablativebody for forming the injector face of an injector. A plurality of portsis disposed in the injector face for injecting propellant into thecombustion chamber and manifold means integrally formed within theablative body is provided for supplying propellant to the ports.

According to one feature of the present invention, the injector isconstructed of a unitary ablative body.

According to another feature of the present invention, a mold isprovided for casting a unitary ablative injector for a rocket engine.

The above and other features of this invention will be more fullyunderstood from the following detailed description and the accompanyingdrawings, in which:

FIG. I is a perspective view in cutaway cross section of a mold for usein constructing an ablative injector according to the presentlypreferred embodiment ofthe present invention;

FIG. 2 is a perspective view in cutaway cross section of a portion ofthe mold illustrated in FIG. 1 for construction of propellant passagesfor an ablative injector according to the presently preferred embodimentof the present invention; and

FIG. 3 is a perspective view in cutaway cross section of an ablativeinjector according to the presently preferred embodiment of the presentinvention.

Referring to FIGS. 1 and 2, there is illustrated a mold for constructionof the ablative injector 12 illustrated in FIG. 3. Mold 10 comprises amain body section 14 having a lower internal surface 16 and cylindricalwalls 18. Center bore 20 is formed in surface 16 of member 14 and araised ring portion 22 extends upwardly from the lower surface 16. Aplurality of cylindrical portions 24 extend upwardly from ring 22 andinclude bores 26 therein. Member 28 (shown in greater detail in FIG. 2)is assembled to member 14 by inserting cylindrical shaft 30 intoaperture 20 of member 14. Member 28 includes toroidal portion 32integral with cylindrical portion 30 and a plurality of cylindricalportions 34 extending upwardly from toroidal portion 32. As illustratedparticularly in FIG. 2, cylindrical portions 34 are arranged in pairsand elliptical apertures 36 are formed through the toroidal portion 32between adjacent ones of each pair of cylindrical portions 34. Asillustratedin FIG. 1, member 28 is assembled to member 14 in such amanner that cylindrical portions 34 are aligned with cylindricalportions 24 of member 14. Apertures 38 are formed in each cylindricalportion 34.

As illustrated in FIG. 1, pins 40 are assembled into apertures 38 oftoroidal portion 32 of member 28. Preferably, pins 40 include a flatheadportion 42. Pins 44 are assembled into apertures 26 of member 14 andextend upwardly through elliptical apertures 36 between adjacent ones ofthe pairs of extrusions 34 in member 28.

Member 46 is assembled to member 14 by assembling member 46 overshoulder 50 of member 14 to fit snugly therewith. Pins 44 extend throughapertures 48 of member 46. Pins 52 are then assembled through apertures54 to abut the heads 42 of pins 40. Surface 56 of member 46 closescavity 58 to form the entire enclosed mold 10.

The completed mold 10 illustrated in FIG. I is then filled with ablativematerial, such as a mixture of quartz and phenolic resin, and the resinis permitted to cure to form the ablative injector 12 illustrated inFIG. 3.

The mold 10 shown in FIG. 1 may be a sacrificial mold in that the mold10, except possibly the pins 40 and 44, melt during the post cure of themolded ablative injector. The mold I0 may be composed of an alloy suchas a tin and zinc alloy or a tin, zinc, and bismuth alloy. The mold 10must retain its strength and shape until the cure temperature exceedsthe temperature of the heat of distortion of the ablative resin. Also,the mold 10 must melt within a temperature range that is above thegelling temperature and below the destruction temperature of theablative material. The melting temperature of the mold alloy may bein'the range of about 400 to 420 F. The pins 40 and 44 may be piano wireof a predetermined gauge and are extracted after the molded injector hasbeen cured. I

Ablative injector 12 illustrated in FIG. 3 comprises a single member 60constructed of ablative material. Injector 12 includes a port 62 (formedby shaft 30 of the mold) adapted to communicate through passage 64 toring passage 66 (formed by toroidal portion 32). Ring passage 66provides divided flows to a plurality of injector ports 68 (formed bypins 40). Injector ports 68 together with ring passage 66, passage 68and port opening 62 are all formed by means of member 28 and pins 40illustrated in FIG. 2. Port opening 62 may be connected by means of asuitable manifold, diagrammatically illustrated at 70, at a supply 72 offuel. Ring port 74 (formed by ring portion 22 of the mold) may beconnected by means ofa suitable manifold, diagrammatically illustratedat 76, to a supply 78 of oxidizer. Ring port 74 is in fluidcommunication with injector ports 80 through passages 82 (formed by pins44). Injector ports 68 and 80 are formed on injector face 84 which isformed by surface 56 of member 46.

The mold illustrated in FIG. I is constructed as hereinbefore describedand filled with an ablative material such as quartz and phenolic resin.The resin is permitted to cure and the mold is disassembled and theablative injector l0 illustrated in FIG. 3 is removed therefrom.

diflii 4ft "Lora n: 5...;

Reliability of the injector is improved by providing a thin lining inthe ports and channels or manifolds. The desired lining may beaccomplished by providing a thin coating of plastic material comprisedof a silicone or fluorocarbon resin. Examples of a plastic material thatis compatible with propellants are E. I. DuPonts Teflon resin orPennsalt Chemical Co.s Kynar resin. The parts of the mold which form theports and manifolds are coated with a thin coating of plastic materialwhich is flash sintered thereon. The thin layer of plastic material isbondized by treating it with a caustic solution such as sodium metal andnapthalene to render the plastic material adherent to the thermosettingor ablative resin of the injector. When the mold material is removed,the molded ablative injector contains ports and channels or manifoldslined with the plastic material thereby preventing interchannel leakage.

' In operation of the ablative injector, the injector is connected tothe combustion chamber of a rocket engine (not shown) and fuel andoxidizer are permitted to pass through the respective ports 68 and 80 ofthe injector face 84. Since ports 68 and 80 are in close proximity toeach other, the fuel and oxidizer are mixed in close proximity to theinjector face 84 in the rocket chamber.

In the event that heat should build up adjacent the injector face duringthe operation of the rocket engine, the ablative materialnondestructively erodes under the influence of the heat. Specifically,in the case of an ablative material formed of quartz and phenolicresins, the heat within the combustion chamber will decompose thephenolic resins to give off a cooling gas so as to maintain the injectorface cool. The remaining quartz builds up an insulating face on theinjection face to thereby reduce the thermal erosion effect.

The present invention thus provides a simple but effective apparatus forconstruction of an effective ablative injector. The injector is easilyconstructed and is effective in use.

This invention is not to be limited by the embodiments shown in thedrawings and described in the descriptions, which are given by way ofexample and not of limitation, but only in accordance with the scope ofthe appended claims.

lclaim:

1. An injector for a rocket engine or the like comprising: an ablativebody forming an injector face adapted to form a wall portion of a rocketcombustion chamber; a plurality of port means in said injector face forinjecting propellant into said combustion chamber; and manifold meansintegrally formed in said body for supplying propellant to saidplurality of port means.

2. An injector according to claim 1 wherein said port means and saidmanifold means are coated with a thin layer of fluorocarbon plasticmaterial.

3. An injector according to claim 1 wherein said port means and saidmanifold means are coated with a thin layer of silicone plasticmaterial.

4. An injector according to claim 1 wherein said plurality of port meanscomprises a plurality of first ports in said injector face and aplurality of second ports in said injector face, and said manifold meanscomprises a first manifold in fluid communication with each of saidfirst ports and adapted to supply an oxidizer to each of said ports anda second manifold in fluid communication with each of said second portsand adapted to supply a fuel to each of said second ports, each of saidfirst ports being in close proximity on said injector face with at leastone associated second port so that oxidizer and fuel will mix in saidcombustion chamber adjacent said injector face.

5. An injector according to claim 4, wherein said first manifoldcomprises a substantially ring-shaped depression in said body open to aside of said body opposite said injector face, and means providing fluidcommunication between said depression and each of said first ports, andsaid second manifold comprises a substantially ring-shaped channel insaid body in fluid communication with each of said second ports, andbore means providing fluid communication between said channel and saidside opposite said injector face, said bore,

said channel, and said depression bein substantially coaxial, and theradius of said bore being less t an the smallest radius of saiddepression.

6. An injector according to claim 5 wherein said body is unitary.

1. An injector for a rocket engine or the like comprising: an ablativebody forming an injector face adapted to form a wall portion of a rocketcombustion chamber; a plurality of port means in said injector face forinjecting propellant into said cOmbustion chamber; and manifold meansintegrally formed in said body for supplying propellant to saidplurality of port means.
 2. An injector according to claim 1 whereinsaid port means and said manifold means are coated with a thin layer offluorocarbon plastic material.
 3. An injector according to claim 1wherein said port means and said manifold means are coated with a thinlayer of silicone plastic material.
 4. An injector according to claim 1wherein said plurality of port means comprises a plurality of firstports in said injector face and a plurality of second ports in saidinjector face, and said manifold means comprises a first manifold influid communication with each of said first ports and adapted to supplyan oxidizer to each of said ports and a second manifold in fluidcommunication with each of said second ports and adapted to supply afuel to each of said second ports, each of said first ports being inclose proximity on said injector face with at least one associatedsecond port so that oxidizer and fuel will mix in said combustionchamber adjacent said injector face.
 5. An injector according to claim4, wherein said first manifold comprises a substantially ring-shapeddepression in said body open to a side of said body opposite saidinjector face, and means providing fluid communication between saiddepression and each of said first ports, and said second manifoldcomprises a substantially ring-shaped channel in said body in fluidcommunication with each of said second ports, and bore means providingfluid communication between said channel and said side opposite saidinjector face, said bore, said channel, and said depression beingsubstantially coaxial, and the radius of said bore being less than thesmallest radius of said depression.
 6. An injector according to claim 5wherein said body is unitary.